This invention relates to a production method of a photosensitive member having a surface protective layer.
Organic photosensitive members are well known. The organic photosensitive member is excellent in sensitivity and chargeability, and costs low for its production.
However, the organic photosensitive members have problems. For example, the surface of organic photosensitive layer is soft. The organic photosensitive member is worn, liable to be injured, and comes to form image-defects and white lines when repeatedly used. The reduction of thickness of the photosensitive member also causes the fall-off of surface potential.
Therefore, a surface protective layer is generally formed on the photosensitive layer in order to overcome the above mentioned problems.
It is desirable that the surface protective layer is formed immediately after the photosensitive layer is formed. But, a number of photosensitive layers are once formed on electrically conductive substrates because of simplification of production and from the view points of a production equipments. And then, surface protective layers, such as amorphous carbon layers or the like, are formed on the photosensitive layers. In general, the photosensitive layers are kept for a few days-a few months until the surface protective layers are formed (this keeping period is referred to as "stock time in process").
The surface of an organic photosensitive layer is oxidized with time by oxygen in the air. When a surface protective layer, such as an amorphous carbon layer, is formed on the organic photosensitive layer, the surface of which is oxidized, the surface protective layer separates off because the adhesivity of the protective layer to the oxidized layer is poor. After only one day passed from the preparation of an organic photosensitive layer, the surface of the organic photosensitive layer is already oxidized to such degree that the surface protective layer is liable to separate off.
By the way, photosensitive members having surface-protective thin layers deposited under vacuum conditions have been known well. But, there is no reference that discloses that a photosensitive layer should be surface-treated in order to secure adhesivity before a thin layer is deposited under vacuum conditions on the photosensitive layer kept for a long time.